Tire chain link with traction members

ABSTRACT

A link for a tire chain including a tread portion and flanking side-wall portions with at least the tread portion including vertically extending links, three or four of which are interconnected by horizontal connectors to form a mesh of a desired shape. The link includes a base portion, a medial portion and a head portion, with at least one traction member of a material that is relatively harder than the material of the link partially embedded in the head portion and partially exposed on the surface of the head portion. The traction member may be in the form of tungsten carbide buttons or plates secured in holes in the head portion of the link or may be in the form of a plurality of particles consolidated in a cemented compact or steel matrix that is secured to the head portion of the link, either by being cast or formed on the head portion or by being provided on a body that is weldable to the head portion.

TECHNICAL FIELD

This invention relates to steel chain links, having applicationprimarily, though not exclusively, in tire chains for heavy dutyvehicles, such as for mining, quarrying, earth-moving and forestryapplications, to protect the rubber tires on one or more axles of suchvehicles and/or provide additional traction.

BACKGROUND ART

Tire chains of the type with which this invention is concerned have atreed portion spanning the tread of a tire and two flanking side-wallportions that respectively span a portion of the inner and outerside-walls of the tire. The chain is composed of links that extendsubstantially normal to the surface of the tire and connecting rings orconnectors interconnecting the links to form a net of a desired pattern.This type of tire chain is referred to as “a tire chain of the type setforth” below.

Tread links each comprise a base portion to provide a smooth, suitablylarge contact area with a tire in use; a medial portion formed with atleast one opening through which a connector can be threaded, with thelateral thickness being reduced relatively to the base portion to permitincreased lateral movement with respect to the connectors; and a headportion of a shape suited to the intended application of the chain. Abroad head portion that may have a diamond shape decreases the meshopening and thereby increases protection, whilst a relatively thinnerhead portion decreases protection and increases traction. Protrusions inthe form of ribs or buttons of the material of the link of variousconfigurations, shapes and sizes may be provided to increase traction,but these have limited long term value as they wear away fairly rapidlyin use, particularly if they are operated in highly abrasive conditionssuch as chrome mines, smelting works and on silica. Whilst increasingthe hardness of the link to inhibit wear is possible, the benefitsobtained are usually more than counteracted by the increased tendency ofthe link to fracture or break in use.

This invention seeks to provide a link for a tire chain that has areduced tendency to slip in use and/or has increased resistance to wear.Optionally the invention seeks to provide a method of modifying a tirechain to increase the traction and/or wear resistance propertiesthereof; to provide a method of restoring tire chains that have worn inuse; and/or to provide parts or components for use in the aforesaidmethods or in a tire chain.

DISCLOSURE OF THE INVENTION

The invention provides a link for a tire chain of the type set forthcomprising a base portion, a medial portion and a head portion,characterised in that the link has at least one traction member of amaterial that is relatively harder than the material of the linkpartially embedded in the head portion and partially exposed on thesurface of the head portion.

The link may have the following features, alone or in combination:

the traction member may be in the form of a solid body, such as acylinder that is preferably substantially round in cross-section or athick plate locked in an opening formed in the head portion of the link;

a plurality of such solid body traction members may be arranged atdesired positions on the head, either adjacent to or spaced apart fromone another;

the traction member may be in the form of a particle in which event aplurality of such particles are preferably consolidated in a cementedcompact or steel matrix;

the traction member is of a suitable hard, abrasion resistant carbide,nitride and the like compounds in particle, cemented or sintered form;

the traction member or members are secured to a body that is weldable tothe head portion of the link. The latter form is particularly suited torestoring links that have worn in use, but may also be used for newchain links.

The invention also includes a tire chain of the type set forthcharacterised by having at least one link of the invention.

Further features, variants, and/or advantages, of the invention willbecome apparent from the following, non-limiting description made withreference to the accompanying schematic drawings of presently preferredexamples of the invention and from the claims, which are to be regardedas an integral part of this description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a portion of a tread portion of a tire chain includinglinks of the invention;

FIG. 2 shows a side view of a link of the invention;

FIG. 3 shows an end view of the link of FIG. 2;

FIG. 4 shows a plan view of the link of FIG. 2;

FIG. 5 shows a side view and a cross-section of an embodiment oftraction member for a link of the invention;

FIG. 6 shows a side view and a cross-section of another embodiment oftraction member for a link of the invention;

FIG. 7 shows a side view and an end view of another embodiment oftraction member for a link of the invention;

FIG. 8 shows a side view and an end view of yet another embodiment oftraction member for a link of the invention;

FIG. 9 shows plan and sectioned side and end views of an embodiment oftread member of the invention; and

FIG. 10 shows plan and sectioned side and end views of yet anotherembodiment of tread member of the invention.

BEST KNOWN MODE FOR CARRYING OUT THE INVENTION AND DESCRIPTION OFPREFERRED EMBODIMENTS

In the drawings the same or similar parts have the same referencenumbers, certain parts having sub-numbers to identify them for thisdescription.

FIG. 1 shows a portion of a tire chain 10 comprising links 12 threadedonto and interconnected by welded ring connectors 14. Four links arethreaded onto each connector to form a mesh with a square pattern. Asshown each link has a diamond shaped head portion that maximises thesurface area covered by the chain for optimum protection. Each link hasthree traction members 15 in the form of stepped-nose, cylindrical,tungsten-carbide button bits. The bits 15 are shown in detail in FIG. 5.

FIGS. 2 to 4 show a link 12.1 comprising a base portion 16, a medialportion 18 formed with two oval eyes or openings 20, and a diamondshaped head portion 22. Stepped layers 24 and 26, each of a diamondshape are formed on the top of the head portion. The stepped layersprovide traction formations to inhibit slipping, ie. increase traction,of the chain. Vertically extending grooves 28 are formed in the edges ofthe head portion 22, the grooves extending in depth to the shoulder ofthe first layer 24. The grooves provides additional grip, which persistsin use even when the stepped layers 24 and 26 have been worn away. Twotraction members 30 in the form of round-nose, cylindrical,tungsten-carbide button bits are brazed into holes in the head portionof the link. The bits 30 are shown in greater detail in FIG. 6.

FIG. 7 shows a substantially rectangular, thick plate traction member 32formed as a sintered tungsten carbide body. This traction member isdimensioned substantially to span the length of the head of a link andhas one of its longitudinal edges bevelled as shown. In use, thetraction member is secured to a link by brazing it into a slot extendingalong the length of the head, with the bevelled edge being exposed. Theupper edge of the bevelled portion need not be flat as shown and mayslope downwards from the centre towards, or vice versa, for increasingits gripping or traction properties in use.

FIG. 8 shows an elongate, rectangular tread member 34 comprising a wearresistant portion 36 and a body portion 38. The wear resistant portion36 forms a traction member and is a compact or matrix of tungstencarbide particles embedded in a suitable steel alloy. The body portion38 is of a weldable steel or cast iron or steel alloy, which may be thesame steel alloy as used to embed the tungsten carbide, and has a loweredge 40 that is bevelled on both sides to facilitate welding it to alink. The lower edge 40 need not be bevelled and can be a flat edge. Thetread member is dimensioned substantially to span the width and lengthof the head of a link. In use, the tread member may be welded to a wornlink, ie. one in which the head has been worn away through use, torestore the link or may be welded to a new link for a new tire chain.

FIG. 9 shows a tread member 42 comprising a substantially rectangularbody 44 having a bevelled lower edge and three button bits 30 pressfitted into holes in the body. The button bits are shorter than theholes into which they are pressed and secured in the holes by peeningthe mouth portions of the holes. This securing method is suited for usewith tire chains that will be used in silica sands, because in use sandparticles enter the hole and wedge between the button bits and the wallsof the holes to secure the button bits. It is not suited for tire chainsthat will be used on, for example, hot slag as the thermal expansion ofthe steel is greater than that of the button bits, so that the holeswiden and the bits fall out.

FIG. 10 shows a tread member 46 comprising a weldable steel body 48 thatis diamond shaped in plan view and two button bits 15 secured in holesin the body by a cross-pin 50. The steel of the body can have a lowhardness for manufacture, eg. about 30 HRC (hardness Rockwell “C” scale)which can then be heat treated to about 55 to 60 HRC after fitting thebutton bits and cross-pin.

Apart from increasing traction the tread members also increase thewearing properties of the link because of their hardness. Typically thetungsten carbide bits or particles have a hardness of 86 to 92 HRA(Rockwell hardness “A” scale) that resists wear and the steel of thelink has a hardness of 50 to 60 HRC that is sufficiently hard incombination with the harder buttons not to wear away unacceptablyrapidly and at the same time soft enough not to be too brittle to breakunder bending forces in use.

The invention is not limited to the precise details described above andshown in the drawings. Modifications may be made and other embodimentsdeveloped without departing from the scope of the invention as definedin the claims.

What is claimed is:
 1. A link for tire chains comprising: a body formedof a metallic first material and including: a base portion adapted tocontact a tire, and a head portion connected to the base portion througha medial portion, and at least one traction member partly embedded inthe head portion and projecting therefrom in a direction away from thebase portion, the traction member formed of a second material harderthan the first material.
 2. The link according to claim 1 wherein thetraction member comprises a solid body fixedly mounted in an openingformed in the head portion.
 3. The link according to claim 2 wherein thetraction member is generally cylindrically shaped.
 4. The link accordingto claim 2 wherein the traction member comprises an elongated plate. 5.The link according to claim 2 wherein the traction member comprises hardparticles consolidated in a cemented compact.
 6. The link according toclaim 5 wherein the traction member comprises hard particlesconsolidated in a steel matrix.
 7. The link according to claim 1 whereinthe traction member comprises carbide particles.
 8. The link accordingto claim 7 wherein the carbide particles are sintered.
 9. The linkaccording to claim 7 wherein the carbide particles are cemented.
 10. Thelink according to claim 1 wherein the traction member comprises nitrideparticles.
 11. The link according to claim 10 wherein the nitrideparticles are sintered.
 12. The link according to claim 10 wherein thenitride particles are cemented.
 13. The link according to claim 1wherein the traction member is secured to a body that is welded to thehead portion.
 14. The link according to claim 1 wherein the medialportion has openings extending therethrough and adapted to receiverespective chain connectors.
 15. A link for tire chains comprising: abody formed of a metallic first material, and including: a base portionadapted to contact a tire, and a head portion connected to the baseportion through a medial portion, the medial portion including openingsadapted to receive chain connectors, and a plurality of traction memberspartly embedded in the head portion and projecting therefrom in adirection away from the base portion, the traction members being brazedin the head portion and formed of a second material harder than thefirst material.
 16. A link for tire chains comprising: a first metallicbody including: a base portion adapted to contact a tire, and a headportion connected to the base portion through a medial portion, themedial portion including openings adapted to receive chain connectors,and a tread member mounted in the body, the tread member including anelongated second metallic body embedded in, and welded to, the headportion, the traction member protruding beyond the head portion andformed of a harder material harder than second bodies.
 17. A tire chaincomprising connecting elements and links fixed to the connectingelements, each link comprising: a body formed of a metallic firstmaterial and including: a base portion adapted to contact a tire, and ahead portion connected to the base portion through a medial portion, andat least one traction member partly embedded in the head portion andprojecting therefrom in a direction away from the base portion, thetraction member formed of a second material harder than the firstmaterial.
 18. The tire chain according to claim 17 wherein theconnecting elements comprise metallic rings, the medial portion of eachlink comprising openings through which respective rings extend, therings being welded to respective links.